The entire disclosure of Japanese Patent Application No. 2008-190202, filed Jul. 23, 2008, is expressly incorporated herein by reference.
1. Technical Field
The present invention relates to a liquid supply device including a supply pump provided in a liquid supply passage, a first unidirectional valve provided on the upstream side of the supply pump, and a second unidirectional valve provided on the downstream side of the supply pump, and a liquid ejecting apparatus.
2. Related Art
In the past, an ink jet printer as a liquid ejecting apparatus printed a text, an image, or the like by ejecting ink droplets onto a target (a sheet, etc.) as a liquid from a printing head. An ink cartridge (a liquid storing member) as an ink supply source supplying ink to the printing head is mounted on such a kind of printer. As an ink supplying method of supplying ink from the ink cartridge to the printing head, there is known a method of using a water head difference based on a difference between an ink surface of the ink cartridge and the height of nozzles of the printing head or a method of supplying ink by use of a pump.
In the ink supply device (a liquid supply device) using the pump, there is known a pressurizing supply method (for example, JP-A-2002-192751 (FIG. 2, etc.)) of supplying ink by sending air pressurized by a pressurizing pump to an ink cartridge and pressurizing an ink pack accommodated in the ink cartridge or a method (JP-A-2006-272661 (FIGS. 2, 4, 6, 8, 10, etc.)) of supplying ink by driving a pump provided in an ink passage and ejecting the ink sucked from an ink cartridge located on the upstream side of the ink passage toward the downstream side of the ink passage.
An ink supply device disclosed in JP-A-2006-272661 includes a pulsation type pump such as a diaphragm type pump and a pair of unidirectional valves (check valves) provided in the upstream side (an input side) and the downstream side (an output side) of the pump, respectively. The unidirectional valve (a first unidirectional valve) on the upstream side is opened by depressurization of the ink upon the sucking drive of the pump, and maintains a valve-closed state when the pressure of the ink is increased upon the ejecting drive of the pump. On the other hand, the unidirectional valve (a second unidirectional valve) on the downstream side maintains a valve-closed state upon the sucking drive of the pump and is opened when the pressure of the ink is increased upon the ejecting drive of the pump.
However, in the ink supply device disclosed in JP-A-2006-272661, since the pump and the first and second unidirectional valves are separate elements, it is necessary to connect these separate elements to each other through pipes such as an ink introducing pipe, an ink outputting pipe, and an air supply tube. For this reason, when the known ink supply device is used, a problem occurs in that the pipes such as tubes are complicated. In particular, since the ink supply devices have to be disposed according to the number of ink colors, the liquid ejecting apparatus such as an ink jet printer has the problem that the number of pipes increases in proportion to the number of ink colors, the pipes become complex, and thus a piping work becomes difficult.